Configured for 24 VDC sinking‑type signal acquisition in SLC 500 backplane networks, the Allen‑Bradley 1746‑IB8 (1746‑IB8 digital input module) provides direct electrical execution of eight discrete input channels with fixed ON/OFF delay characteristics.
Hardware Specifications
Parameter
Specification
Model
1746‑IB8
Brand
Allen‑Bradley
Origin
Not specified
Weight
Not specified
Dimensions
Not specified
Operating Temp
Not specified
Power Consumption
0.050 A @ 5 VDC (backplane), 0.0 A @ 24 VDC
Product Type
Digital Input Modules
Series
SLC 500 (1746)
Voltage Category
24 VDC sinking
Number of Inputs
8
Points per Common
8
Operating Voltage
10–30 VDC
Signal Delay
8 ms ON, 8 ms OFF
Off‑State Voltage
5.0 VDC max
Off‑State Current
1 mA max
Input Current
8 mA @ 24 VDC
Backplane Bus Communication Velocity Licenses
The 1746‑IB8 participates in deterministic backplane communication used across Allen‑Bradley SLC 500 architectures. Each input channel is sampled at fixed intervals defined by the processor’s scan cycle, ensuring predictable state recognition. I/O density scaling allows multiple digital modules to coexist without altering propagation timing. Firmware flash compatibility resides entirely within the SLC processor; the IB8 contains no programmable logic and provides stable, passive input behavior across controller revisions.
Frequently Asked Questions
Q: Can the 1746‑IB8 be hot‑swapped? A: No. The module must be inserted or removed only when the chassis is de‑energized to avoid backplane faults.
Q: Does the module support sourcing inputs? A: No. The 1746‑IB8 is designed exclusively for sinking input configurations.
Q: How do the fixed 8 ms delays affect input detection? A: The ON/OFF delay defines the minimum transition time required for reliable state recognition during the processor scan.
Field Installation Guidelines
Route 24 VDC input wiring separately from high‑energy conductors to reduce noise coupling.
Maintain correct polarity for sinking devices to avoid false input states.
Ensure terminal screws are tightened to manufacturer torque recommendations.
Verify backplane power capacity when installing multiple digital modules.
Label field wiring to support maintenance and troubleshooting.
Maintain non‑condensing humidity conditions to prevent terminal oxidation.
